Dear Ms. Finnegan,
Thank you for posting your request on History Hub!
We searched the National Archives Catalog and located World War II Operations Reports, 1940-1948 in the Records of the Adjutant General's Office, 1917-1981 (Record Group 407) that may contain unit records of the 5th Field Artillery Sound-Ranging Platoon. For more information about these records, please contact the National Archives at College Park - Textual Reference (RDT2) via email at email@example.com.
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We searched online and located DTIC ADA112018: A Checklist of Artillery Organizational Histories; A Compilation that lists a history of the 5th Field Artillery Sound-Ranging Platoon in the custody of the Morris Swett Library, Fort Sill, Oklahoma.
We also located “The Field Artillery Journal” November - December 1948 edition, which has an article entitled “The Field Artillery Observation Battalion” (starting on page 252) which references the formation of separate, numbered sound ranging platoons on page 253. It refers to the deployment of the First through Fourth Sound-Ranging Platoons in the Pacific Theater. The article also gives an overview of the practice of field artillery range sounding.
In addition, we located http://www.cbi-history.com/part_xi.html and http://www.cbi-theater.com/ramgarh/ramgarh.html that reference the 5th Field Artillery Sound-Ranging Platoon in the Chinese-Burma-India Theater, and an obituary of Vic Tamashunas, which briefly describes his time in the 5th Field Artillery Sound-Ranging Platoon.
Finally, we located Technical Manual 12-427-- Military Occupational Classification of Enlisted Personnel, published by the War Department on 12 July 1944. Pages 48 through 49 describe the roles of a Geodetic Computer.
We hope this information is helpful. Best of luck with your research!